Christopher, I am not an electrical guru, but it seems like there are two different items being compared here. JMHO
Mike G and Robert M are both correct. The neutral would be carrying the additive current of two hot conductors fed from one bus.
Jim,
Mike G and Robert M are NOT correct. They do NOT know what a Multi-Wire Branch Circuit is. A multi-wire branch circuit is NOT The same thing as two circuits being fed from the same busbar.
Don’t believe me if you don’t want to. There are many sources where you can learn about multi-wire branch circuits. You can start with the National Electrical Code. Anyone who claims that the neutral on a multi-wire branch circuit can be overloaded is clueless.
Mike G, Robert M and others seem to think that any time there are two ungrounded conductors, they have a multi-wire branch circuit. That is complete and utter nonsense. That is like saying a chicken and a horse are the same because they both have legs.
Any apprentice electrician should understand what a multi-wire branch circuit is well within the first year.
Personally, I am thoroughly disgusted with the way Non-members post BS and mislead Members in this forum. I am here ONLY for the benefit of Members who want to learn. I don’t give a crap about Non-Members who CLAIM to be electricians. If they don’t know what a multi-wire branch circuit is, they need to go back to school because it doesn’t get much more basic than that.
Any Member who doubts me can do their own research. The National Electrical Code and many other texts define what a multi-wire branch circuit is.
Saying that two circuits or more circuits on the same leg sharing a neutral is a multi-wire branch circuit is a demonstration of incompetence as an electrician and a disservice to InterNACHI Members who are trying to learn.
As an InterNACHI Member, my commitment to fellow Members is to always help to the best of my ability.
That is wrong. Potential is Voltage, not current.
I am wrong about what?
Correct. My apologies. How about the rest of the post. Please explain how this has no potential to be unsafe.
That this is fine. You are wrapped in the semantics of MWBC and pufferfishing your qualifications. You are overlooking the issues that this setup could create.
You say you are looking out for inspectors while hammering on others that are daily contributors as guests to our board. I for one trust Robert and his expertise.
wrong again. Reading comprehension would help you. I think i actually explained that this is not the proper definition if the issue but you overlooked that.
Correct, and while not technically a MWBC, it is an attempt at it and a miswired one… You know exactly what is being discussed! and you know why we all call it MWBC even if there is no potential between the two ungrounded conductors of that circuit.
1 Like
Larry,
I almost never tell home inspectors to go to the NEC for information but in this case, I suggest that anyone following this discussion go to the NEC to see what a multi-wire branch circuit is.
A Multi-Wire Branch Circuit According to NEC Article 100
A multiwire branch circuit consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system. (Basically, two hot wires are sharing a neutral wire.)
Look up fhe definition. Then, use a Volt meter in any residential electrical panel to measure the Voltage between ANY TWO CONDUCTORS ON THE SAME LEG. The reading will be ZERO.
Then, go back through this discussion and read the comments by the numb-nuts who say that two conductors on the same leg are a multi-wire branch circuit and that the currents are ADDED instead of the neutral current being the difference of the currents on the ungrounded conductors in a Multi-Wire Branch Circuit.
I am amazed that these so-called electricians don’t know what a multi-wire branch circuit is.
Like I’ve said several times, InterNACHI Members can do their own research. This is the Internet. Anyone can post any BS that they want. Members can find multiple credible sources both online and offline to learn what a multi-wire branch circuit is.
No. Mike Holt knows what a a multi-wire branch circuit is. I know what a multi-wire branch circuit is. Read the definition in the NEC.
Thank you Simon. Others luckily can see through the rant of qualifications getting in the way of the real issue.
Thank you, George.
1 Like
This is from the 2020 edition of the National,Electrical Code. In the panel that is the subject of this discussion, there is no Voltage between the B and C busbars. Therefore, two circuits connected to them are just that, two circuits, not a Multi-Wire Branch Circuit.
Merely having two ungrounded conductors does not make a Multi-Wire Branch Circuit. I don’t know how it can be made any clearer than what the NEC has done.
I jumped into this discussion because Robert M said that putting two circuits on the same leg would be creating a Multi-Wire Branch Circuit and that the neutral on a Multi-Wire Branch Circuit can be overloaded. He is wrong according to the NEC and what a Multi-Wire Branch Circuit is generally understood to be in the electrical industry.
All I can do at this point is to encourage home inspectors to do their own research. I did searches on both Bing and Google for information related to Multi-Wire Branch Circuits and found probably a hundred or more (I didn’t count them) definitions, articles, and images.
George, Aside from the Multi-branch discussion, in your professional opinion, what issues would you have with the panel I have in the OP?
A miswired MWBC, the object under discussion, could have up to 2x the neutral current the conductor is rated for.
There is no need for the NEC to supply a definition for something that is miswired. That does not remove the potential hazard that some continue to ignore. The same hazard would exist if someone wired a xx-3 cable to a tandem or if the black and red were not placed on adjacent breakers and landed on the same leg.
1 Like
Where are they?